Process for preparing ethylenically unsaturated isocyanurates

Abstract

Process for the preparation of ethylenically unsaturated isocyanurates comprising reacting polyisocyanate with a monohydric alcohol containing a vinylidene group in the presence of a copper salt to form an isocyanate-containing urethane and then trimerizing the isocyanate-containing urethane to form an ethylenically unsaturated isocyanurate. The ethylenically unsaturated isocyanurate may be homopolymerized or copolymerized with ethylenically unsaturated monomers to form high molecular weight polymers having excellent physical properties.

Having described the invention, what is desired to be secured by Letters Patent is: 
     
       1. A process for preparing an ethylenically unsaturated isocyanurate which comprises reacting a polyisocyanate with a monohydric alcohol which contains a vinylidene group and which does not contain an allyl group, in the presence of a copper salt to form an isocyanate-containing urethane, wherein the amounts of monohydric alcohol and polyisocyanate are selected to furnish after said reaction from 0.75 to 1.6 moles of unreacted isocyanate groups per mole of polyisocyanate used, then adding a catalytic amount of an isocyanate trimerization catalyst which will initiate trimerization of the isocyanate-containing urethane without causing gellation, and trimerizing the isocyanate-containing urethane to form an ethylenically unsaturated isocyanurate. 
     
     
       2. A process of claim 1 wherein the organic polyisocyanate is an aromatic polyisocyanate. 
     
     
       3. A process of claim 2 wherein the monohydric alcohol is hydroxypropyl methacrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxyethyl acrylate, pentaerythritol triacrylate, pentaerythritol trimethacrylate, or mixtures thereof. 
     
     
       4. A process of claim 3 wherein the aromatic isocyanate is tolylene diisocyanate. 
     
     
       5. A process of claim 4 wherein the copper salt is cupric acetate. 
     
     
       6. A process of claim 1 which comprises (a) preparing a solution of a copper salt, a free radical polymerization inhibitor, and a monohydric alcohol, said alcohol containing a vinylidene group, in a solvent which is unreactive with isocyanate groups, (b) slowly adding a trimerizable organic polyisocyanate to the solution in the presence of sufficient oxygen to keep the inhibitor active and while maintaining the temperature of the solution from 10° C. to 130° C. to form an isocyanate-containing monourethane, (c) adding a catalytic amount of a trimerization catalyst which will initiate trimerization of the monourethane without causing gellation of the monourethane, and (d) maintaining the temperature from 0° C. to 95° C. to form an isocyanurate. 
     
     
       7. A process of claim 6 wherein the organic polyisocyanate is an aromatic diisocyanate. 
     
     
       8. A process of claim 6 wherein the organic polyisocyanate is a tolylene diisocyanate. 
     
     
       9. A process of claim 7 wherein the alcohol is hydroxypropyl methacrylate. 
     
     
       10. A process of claim 7 wherein the alcohol is hydroxyethyl methacrylate. 
     
     
       11. A process of claim 7 wherein the alcohol is hydroxyethyl acrylate. 
     
     
       12. A process of claim 7 wherein the monohydric alcohol is hydroxypropyl acrylate. 
     
     
       13. A process of claim 7 wherein the alcohol is a mixture of hydroxypropyl methacrylate and hydroxyethyl methacrylate. 
     
     
       14. A process of claim 7 wherein the solvent is an aromatic hydrocarbon. 
     
     
       15. A process of claim 7 wherein the solvent is a vinylidene monomer. 
     
     
       16. A process of claim 7 wherein the solvent is selected from the group consisting of styrene, benzene, methyl methacrylate, divinylbenzene, ethyl methacrylate, dioxane, ethyl acrylate, ethyl acetate, and methyl ethyl ketone. 
     
     
       17. A process of claim 7 wherein the trimerization catalyst is tributyl phosphine. 
     
     
       18. A process of claim 7 wherein the trimerization catalyst is N-benzyltrimethylammonium hydroxide. 
     
     
       19. A process of claim 7 wherein the trimerization temperature is from 20° C. to 65° C. 
     
     
       20. A process of claim 7 wherein the amount of solvent is from about 30% to about 80% by weight of the weight of the total composition. 
     
     
       21. A process of claim 7 wherein the copper salt is cupric acetate. 
     
     
       22. A process of claim 20 wherein the monohydric alcohol is selected from the group consisting of hydroxypropyl methacrylate, hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, and mixtures thereof, the solvent is styrene, the polyisocyanate is a tolylene diisocyanate, the copper salt is cupric acetate, the trimerization catalyst is N-benzyltrimethylammonium hydroxide, and the trimerization temperature is from 20° C. to 65° C. 
     
     
       23. A process of claim 22 wherein the monohydric alcohol is hyroxypropyl methacrylate, hydroxyethyl methacrylate or mixtures thereof. 
     
     
       24. A process of claim 23 wherein the free radical polymerization inhibitor is hydroquinone, tertiary butyl catechol, monomethyl ether or hydroquinone, or mixtures thereof. 
     
     
       25. A process of claim 1 wherein the trimerization catalyst is neutralized with an acid after the formation of the ethylenically unsaturated isocyanurate. 
     
     
       26. A process of claim 25 wherein the acid is methanesulfonic or a mixture of methanesulfonic acid and oxalic acid. 
     
     
       27. A process of claim 25 wherein a low molecular weight alcohol or secondary amine is added prior to the addition of the acid. 
     
     
       28. A process of claim 3 wherein the copper salt is a cupric salt. 
     
     
       29. A process of claim 3 wherein the copper salt is a cuprous salt. 
     
     
       30. A process of claim 3 wherein the urethane forming reaction and the trimerization reaction are conducted in the absence of a solvent. 
     
     
       31. A process of claim 1 wherein the monohydric alcohol contains an ester group.